Re: first 7mag loads
If you would like a simple tool to aid in seating depth, you can get a Stoney Point bullet depth gauge from Midwayusa.com
It is good that you've had success by visual inspection in the past. However, if you want to know the numbers, I recommend a gauge. It comes with any dummy brass you want and extra calibers are not that expensive.
When I checked my 7mag with the 120 tsx, it was seated so far out that minimal bearing surface of the bullet was in the neck. Not enough tension IMO. The rifle still printed 1.2" groups but that is not what I'm looking for. As I seated it deeper, the groups spread.